Low-Complexity Multi-User Parameterized Beamforming in Massive MIMO Systems

Geon-Woong Jung,Yong-Hwan Lee

doi:10.3390/electronics9060882

Abstract

In this paper, we design a complexity-reduced transmission scheme in massive antenna environments. To reduce the implementation complexity for the generation of beam weight, we design a multi-user parameterized beamforming (MUPB) scheme that can control the beam direction using a single parameter with combined use of maximum ratio transmission and partial zero-forcing scheme that partially nulls out interference. We design the MUPB to maximize the signal-to-leakage plus noise ratio (SLNR). To further reduce the implementation complexity, we optimize the MUPB based on approximated SLNR instead of accurate SLNR. Finally, the performance of the proposed MUPB is verified by computer simulation.

Highlights

The use of massive multi-input multi-output (m-MIMO) techniques has widely been applied to advanced wireless communication systems [1,2,3]
The use of zero-forcing (ZF) beamforming can be a practical choice in m-MIMO environments since it may null out inter-user interference [6,7,8]
We consider the use of a partial ZF (PZF) beamforming technique that selectively nulls out interference, making it possible to reduce the dimension of nulling subspace

Summary

Introduction

The use of massive multi-input multi-output (m-MIMO) techniques has widely been applied to advanced wireless communication systems [1,2,3]. The use of zero-forcing (ZF) beamforming can be a practical choice in m-MIMO environments since it may null out inter-user interference [6,7,8] It may require large computational complexity for the generation of beam weight in m-MIMO environments. The Max SLNR technique maximizes the SLNR by applying Rayleigh–Ritz quotient theorem [22,23] It may require computational complexity in cubic proportion to the number of antennas, which may be unaffordable in m-MIMO environments. As the number of users increases, the ZF may experience the presence of insufficient spatial DoF, yielding poor performance of PB in multi-user environments To alleviate this problem, we consider the use of a partial ZF (PZF) beamforming technique that selectively nulls out interference, making it possible to reduce the dimension of nulling subspace (i.e., to exploit more spatial DoF).

System Model

Proposed Beamforming Scheme

Behavior according to parameter

Computational Complexity

Performance Verification

Conclusions